Automatic telephone system



July 29, 192 1,502,916

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM 0 Filed July 23, 1919 CONHECTDR.

SELECTOR.

i i E I H INVENTOR wmFRED T. POWELL.

ATIORNEY LINE SWITCH.

Patented July 29, 1924.

sierra vrear OFFICE.

WINFRED 'I. POWELL, OF ROCHESTER, NEW YORK, ASSIGNOB TO THE S TBOMIBERG;CARLSON TELEPHONE MANUFACTURING- GO MPANY, OF ROCHESTER, NEVJ YORK, A

CORPORATION OF NEW. YORK.

auroraa'rrc TELEPHONE SYSTEM.

Application filed July 23, 1919. Serial No. 312,524.

1 "0 all whom it may concern:

Be it known that I, VVINFRED T. POWELL, a citizen of the United States,residing at Rochester,- in the county of Monroe and State of New York,have invented certain new and useful Improvements in Automatic TelephoneSystems, of which the following is a full, clear, concise, and exactdescription,

This invention relates to telephone systems, and more particularly totelephone systems employing machine switching in establishingconversational circuits between calling and called subscribers.

The present invention has for its purpose the simplification of circuitsof the numerical and non-numerical switches employed in automatictelephone systems. It is proposed in these circuits to reduce the numberof controlling electromagnets or relays without diminishing the speed ofoperation of the switches and without lessening the reliability of thevarious testing operations. fizz Other features not specificallyenumerated will appear from the following detailed de scription and theappended claims.

@The drawing diagrammatically represents aportion of a telephone systemin which the circuits of the present invention have been incorporated.The portion of the drawing at the left of the dotted lines representsthe substation circuits of a calling line, as well as the operatingcircuits of a line switch individual to this'line, The portion of thedrawing included between the two dotted lines-represents the operatingcircuits of a selector or a connector switch, while at the right of thedotted lines there is shown the release magnet and the firstslow-releasing relay of a second selector or a connector switch circuitthrough which the called substation may be reached.

The line switch may be of any-form of rotary line switch that has nonormal position, while the selector switch may be of'the type similar tothat shown in the patent to Keith 'et al., No. 815,321, issued March13th,

1-906, when modified to operate without a side switch in a so-calledtwo-wire system.

The connector or second selector circuits of which only the firstslow-releasing relay and release "magnet are shown, may be similartoiany selector or connector circuits employingzfast afidf slow relayseither with or without a so-called side switch when modified asindicated at the extreme right of the drawing.

It is believed that the invention will best be understood by describingthe operation of establishing a connection between a calling substationA and a called substation B. Whenthe calling subscriber at A removes hisreceiver fromits switchhook, the line relay LR is energized over acircuit extending from grounded battery, winding of the line relay,inner back contact and armature of the cut-off relay CO, upper side ofthe calling line and its substation circuits, lower side of the callingline, outer armature and back contact of the cut-o5 relay to ground. Theline relay LR is energized in this circuitand attracts its armatures.With the line relay LR energized, when the brushes of the line switchare in engagement with the terminals of a busy trunk, an operatingcircuit for the motor magnet MM is closed from grounded battery,winding, armature and back contact of the motor magnet outer frontcontact and armature of the line relay, lowermost armature and backcontact oi relay 5, test brush 6, test terminal 7 of the busy trunk. toground over aline switch test brush similar to 6, lowermost armature andfront contact 013 relay similar to 5, to ground at the line switch thathas previously seized the trunk being tested.

Under the control of a circuit similar to that just described, the motormagnet continues toadvance its brushes 8', 9, 10 and 6 until its testbrush 6 encounters the test terminal characterized by the absence ofground, a condition which indicates that the trunk is idle. As soon asthe idle trunk is reached, the cut-off relay CO and the relay 5 areenergized in series in a circuit traceable from grounded battery,winding of the motor magnet MM, armature and back contact of thismagnet, winding of the cutoff relay CO, inner front contact and armatureof the line rela y LR, conductor 11, winding of' the relay 5, brush 10.of the line switch and holding terminal of the idle trunk, conductor 12,armature and back contact of release magnet 28 to ground. The motormagnet MM is not energized inthis circuit,

but the relays 5 and C0 are energized and attract their armatures, Thecut-ofi relay COdisconnectsthe line relaysfrom the call Ill ing line,but before this takes place a substitute circuit is completed for thecut-off relay CO from grounded battery, winding and back contact of themotor magnet MM. Winding of the cut-off relay, conductor 14- inner frontcontact and lower armature of relay 5, conductor 11, winding of therelay 5, brush 10 of the line switch, the holding terminal of the trunkseized, to ground over conductor 12 at magnet 28.

As soon as the relay 5 attracts its armatures. the stepping relay SR ofthe selector switch is energized over a circuit completed from groundedbattery. right hand winding of this relay, conductor 16, uppermost backcontact and armature of relay 15. brush 8 of the line switch, uppermostfrontcontact and armature of the relay 5. through the substationcircuits of the calling line A, inner, upper armature and front contactof the relay 5. brush 9 of the line switch, middle armature and backcontact of the relay 1:). left hand winding of the stepping relay SE. toground. The step pingrelay S'R attracts its armatures and maintains themactuated until the calling subscriber operates his substation sender. Atthe outer armature and front contact of the stepping relay SR, anoperating circuit is closed for the slow-releasing relay 13. whichattracts its armature. Atthe armature and back contact of relay 18, theoperating circuit of the release magnet 28 is opened. thus preventingthe release of the switch, and at its armature and front contact a breakpoint in the operating circuit of the primary motor magnet PM is closed.

As soon as the calling subscriber at A operates his substation sender,the stepping relay RR vibrates its armatures in the well known manner tocomplete an operating circuit for the primary motor magnet PM. fromgrounded battery. winding of this magnet. winding of the slow-releasingrelay 17, front contact and armature of relay 13, conductor 18,lowermost armature and back contact of relay 15, outer back contact andarmature of steppingrelay SR. to ground. The primary motor magnet isthus operated in response to each impulse transmitted to the steppingrelay SR. and advances the brushes of the selector switch. stepby-stepin its group selecting movement. The slow-releasing relay 17 as is wellknown. is so adjusted that it will not retract its armature duringmomentary interruptions of its operating circuit. but will only retractits armature at the close of a series of impulses.

lVhen the selector switch has completed its directive movements underthe control of the substation sender and has selected a group of trunksover one of which the calling line may be extended. the selector switchthen begins its automatic operation to hunt for an idle trunk in theselected group. The primary magnet is no longer efi'ective since itsoperating circuit is held open at the attracted armature of the steppingrelay SR. but the secondary motor magnet Sill. however, is operated overa circuit closed from grounded battery. wind ing of this magnet.continuity contact and spring of the relay 1:), conductor 19. inner backcontact and armature of; secondary motor magnet SM. conductor 20, innerarmature and front contact of stepping relay SR, back contact andarmature of relay 17. off normal contact and spring 31. to ground. Fnderthe control of this circuit. the secondary motor magnet advances thebrushes of the selector into engagement with the first trunk of theselected group. lf this trunk is idle. it will be seized in a manner tobe described. but if this trunk is busy, the secondary magnet SM willcontinue to interrupt its local current extending to ground at offnormal contact 31. to advance the brushes 2].. 2G and 27 of the selectorover the terminals of busy trunks. 'l he idle condition of the trunk isindicated by direct ground on its test terminal. while a busy conditionof the line is indicated by ground through a relatively high resistance.Let it be assumed that the second trunk tested. which is the trunk shownin the drawing is idle so that as soon as the test brush of the selectorengages the test terminal of this trunk. the secondary magnetismaintained energized for a relatively long interval over a circuit nowtraced from Q'IOlillflfll battery. winding of the secondary motor magnet9 M. continuity contact and spring of relay 15. test brush 21, testterminal oi": the idle trunk. back contact and armature of the firstslow-releasing relay of'the selector. or connector as the case may be.back contact and armature of the release magnet 23. to ground. Since thesecondary motor magnet is energized for a comparatively long time. itattracts its sluggish armature Ql which has previously remained inactiveand this operation closes a circuit for operating the relay 15. Thiscircuit extends from grounded battery. winding of this relay. conductor25, front contact and armature 24 of the secondary motor magnet SM. toground. The relay attracts its armatures extending the calling linethrough the brushes 26 and 27 of the selector-to the idle trunk. anddisconnects the stepping relay SR. At the lowermost armature and backcontact of relay 1:"). the operating circuit of the primary motor magnetPM is openethand at the contact and continuity spring of this relay theenergizing circuit of the secondary motor magnet SM isinterrupted. Therelay in also closes a locking circuit for itself at this time fromgrounded battery,

its Winding, lower armature'and continuity spring, test brush 21 of theselector to ground at the armature and back contact of the releasemagnet 23, through the high resistance or through the contact andarmature of the slow-releasing relay 22. The connection, may then beextended to an idle trunk leading to a connector through theoperation ofa second selector, the operating circuits of which are similar to thecircuits of the selector just described. "For purposes of thisdescription, however, it has been assumed that the first selector willselect a trunk leading to a connector which will seize and signal thewanted line in any well known manner.

A connector switch circuit is shown in the patent to Powell, No.1,165,709, patented Dec. 28th, 1915, which will operate with the presentselector switch circuits when modi-- lied as indicated at the extremeright of the present drawing. It will be readily understood from thelast mentioned patent that the talking battery for the calling andcalled parties as well as the release of the connection is controlled atthe connector switch.

At the close of the conversation, the release magnet 23 of the connectorwill be energized, due to the fact that the calling party has terminatedthe call, to open the holding circuit of the relay 15, causing thisrelay to retract its arm atures. A circuit will thereupon be completedfor the release mag net 28 ot the selector from grounded battery,winding of the magnet 28, off normal contact and spring 29, inner backcontact and armature of relay 13, conductor 18, lower-most armatureandbaclu contact of relay '15, outer backcontact and armature of relaySR to ground. At the armature and contact of release magnet 28, theholding circuit of the relay 5and cut-oft relay G0 are opened toreconnect the line relay LE to the calling line, and to disconnect thebrushes 8 and 9 ol the line switch from this line, The apparatus andcircuits are now in condition to handle another call. 7 It will be notedthat an improved selector switch has been provided in which no sideswitches are employed and wherein a minimum number of relays arenecessary to insure rapid hunting for idle trunks, and re-: liabletesting of these trunks tor a busy: or idle condition. The line switchcircuit likewise employs a minimum number of relays and is swift andreliable in operation.

hat I claim is:

1. In a telephone systen' an automatic switchgpriihary and secondarymagnets for operating saidswitch, a primary circuit for said primarymagnet, an initial energizing circuit for said secondary ma net local tosaid switch, and a substitute clrcuit including the winding of saidsecondary magnet and completed at a point remote from aid switch, andreleasing means therefor.

2. In a telephone system, an incoming line, a plurality of outgoinglines, a switch having primary and secondary movements to interconnectsaid incoming line with any of said outgoing lines, means for indicatingthe busy'or idlecondition of each of said outgoing lines, means foradvancing said switch in its primary movement, and a secondary magnetfor advancing said switch in'its secondary movement, said secondarymagnet serving to test for idle lines and to maintain itself actuatedwhen an idle line is'fouiid. Y

3. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any of saidoutgoing lines, an impulse relay normally connected to said incomingline and responsive to impulses from a distant point, brushes for saidswitch normally disconnected from said incoming line, controlling meansoperative to disconnect said inf coming line from said impulse relay andto extend it to the brushes of said switch, primary operating means forsaid switch controlled at said impulse relay, a secondary magnettherefor, a circuit for said secondary magnet having multiple branches,one of said branches being completed at said switch, and the otherbranch of said circuit beingextended by said controlling means to aremote point. i 1 a 4. In a telephone system, an incoming line. aplurality of outgoing lines, a switch for interconnecting saidincomingline with any of said outgoing lines, an'impulse relay normallyconnected to said incoming line and responsiv'e to impulses from adistant point, brushes for said switch normally dis connected from saidincoming line, controlling means operative to disconnect said incomingline from said impulse relay and to extend it tothe brushes of saidswitchjprimary operating means for said switch controlled at saidimpulse relay, a secondary magnet therefor. a circuit for said secondarymagnet having multiple branches, one of said branches being completed atsaid switch, and the other branch of said circuit being completed atsaid controlling means andat one of the brushes of said switch.

In a telephone system, an automatic switch,' pr'iinary and secondaryoperating n'iagnets for said switch, a circuit for said primary magnet,and a circuit for said secondary magnet having multiple branches, onebranch being completed to operate said switch, and the other branchbeing completed to sto said switch.

6. In a te ephone system, an incoming line, a plurality of outgoinglines, an automatic switch for interconnecting said incoming line withany of said outgoing lines, a mechanical switch associated therewith, animpulse relay normally connected to said incoming line and responsivet'e impulses from a distant point, brushes for said switch normallydisconnected from said incoming line, controlling means operative todisconnect said incoming line from said impulse relay and to extend itto the brushes of said switch, primary operating means for said switchcontrolled at said impulse relay, a secondary magnet therefor, and acircuit for said secondary magnet jointly gov rned by said controllingmeans, by said impulse relay and by said mechanical switch.

7. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said'incoming line with any of saidoutgoing lines, an impulse relay normally connected to' said incomingline and responsive to impulses from a dist-ant point, brushes for saidswitch normally disconnected from said incoming line, controlling meansoperative to disconnect said incoming line from said impulse relay andto extend it to the brushes of said switch, primary operating means forsaid switch controlled at said impulse relay, secondary operating meansfor said switch, and a circuit for said controlling means completed bysaid secondary operating means.

8. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any of saidoutgoing lines, an impulse relay normally connected to said incomingline and responsive to impulses from a distant point, brushes for saidswitch normally disconnected from. said incoming line, controlling meansoperative to disconnect said incoming line from said impulse relay andto extend it to the brushes of said switch, primary operating means forsaid switch controlled at said impulse relay, a secondary magnettherefor, and circuits for said secondary magnet and controlling meanshaving multiple branches, one branch to actuate and the other branch tohold actuated said secondary magnet and said controlling means.

9. In a telephone system, an automatic switch, primary and secondaryoperating magnets for said switch, circuits for said magnets, andcontrolling means for said switch, said secondary magnet being providedwith armatures operating in dilferent time intervals to advance saidswitch and to actuate said controlling means.

10. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any of saidoutgoing lines, an impulse relay normally connected to said incomingline and responsive to impulses from a distant point, brushes for saidswitch, normally disconnected from said incoming line, a con trollingdevice operative to disconnect said incoming line from said impulserelay and to extend it to the brushes of said switch,

prin'iary operating means for said switch controlled at said impulserelay, a secondary operating device for said switch, and initialoperating circuits for said devices, the operating circuit for eachdevice being completed at the other device.

11. In a telephone system, an incoming circuit, a plurality of outgoingcircuits, an automatic switch for intercomiecting said incoming circuitwith any of said outgoing circuits, oii'normal contacts on said switch,an impulse relay responsive to impulses transmitted over said incomingcircuit, said impulse relay having front contact, a primary motor magnetfor said switch arranged to be directively controlled by said impulserelay, a secondary motor magnet for said switch, and a circuit extendingthrough the winding of the secondary motor magnet and completed at frontcontacts of said impulse relay and said oft-normal contacts.

12. In a telephone system, an incoming line, a plurality of outgoinglines, a switch for interconnecting said incoming line with any of saidoutgoing lines provided with olfnormal contacts, an impulse relaynormally connected to said incoming line responsive to impulses from adistant point, brushes for said switch normally disconnected from saidincoming line, a controlling relay operative to disconnect said incomingline from said impulse relay and to extend it to the brushes of saidswitch, a slow acting relay operated by said impulse relay to controlthe release of said switch, a primary motor magnet, a circuit thereforcontrolled at said slow acting relay, said controlling relay and saidimpulse relay, a change-over relay in series with said primary motormagnet, a secondary motor magnet for said switch, and a cir cuit forsaid secondary motor magnet controlled at contacts of said controllingrelay, said impulse relay, said change-over relay and said off-normalcontacts.

In witness whereof, I hereunto subscribe my name this 22nd day of July,A. D. 1919.

WVINFRED T. POWELL.

